A&P2 BIO142 LAB 5: Blood Vessels

the smallest vessels of the arterial circulation and are the vessels that transport blood into capillary beds. The tunica media of arterioles can consist of 1-6 layers of smooth muscle, with the smallest vessels only containing a single layer.

Arterioles [histological features of arterioles and types of arteries]

The axillary artery is a continuation of the subclavian artery. The name change occurs as the subclavian artery crosses the first rib. It courses through the axilla posterior to the pectoralis minor muscle and is surrounded by the cords of the brachial plexus. When it crosses the inferior border of the teres major muscle, the name changes to the brachial artery. It supplies oxygenated blood to the lateral thoracic wall, the shoulder, pectoral region, the axilla, and upper limb.

Axillary artery (right and left) [Arteries of thorax, head, and upper extremity]

The axillary vein is formed by the union of the basilic vein and brachial veins at the inferior border of the teres major muscle. It courses through the axilla to continue as the subclavian vein. It drains the shoulder, lateral thorax, and upper extremity.

Axillary vein (right and left) [Veins of thorax, head, and upper extremity]

The basilica vein is a large superficial vein along most of its course. It ascends from the hand along the anterior-medial forearm and arm to join with the brachial vein at the inferior border of the teres major muscle. It drains the hand, forearm, and arm.

Basilic vein (right and left) [Veins of thorax, head, and upper extremity]

The brachial artery is a continuation of axillary artery. The name change occurs when the axillary artery crosses the inferior border of the teres major muscle. It descends through the arm along the medial border of the biceps brachi muscle. In the distal arm it passes deep to the bicipitial aponeurosis into the anterior elbow (cubital fossa). It terminates by dividing into the radial and ulnar arteries in the antecubital fossa. It supplies oxygenated blood to the anterior arm, forearm, and hand.

Brachial artery (right and left) [Arteries of thorax, head, and upper extremity]

The brachial veins are considered vena comitantes, which means they are accompanying veins of the brachial artery. Usually two brachial veins, connected to each other by short transverse vessels, are present on either side of the brachial artery. The brachial veins are formed by the union of the radial and ulnar veins. The pair of veins course through the arm on either side of the radial artery and ultimately become the axillary vein at the inferior border of the teres major muscle. The basilic vein joins with the brachial vein just distal to the inferior border of the teres major muscle.

Brachial veins (right and left) [Veins of thorax, head, and upper extremity]

The brachiocephalic veins are formed by the union of the internal jugular veins and the subclavian veins. They drain blood from the head and the upper extremity.

Brachiocephalic vein (left and right) [Veins of thorax, head, and upper extremity]

microscopic vessels supplied by arterioles and drained by venules. The wall of a capillary consists of only a tunica intima. Capillaries are the site of nutrient, blood gas, and waste exchange between the cells of the body and the blood. Histologically, capillaries are identified by their thin walls and small size. The lumenal diameter of a capillary is about the diameter of one red blood cell.

Capillaries [histological features of capillary]

The cephalic vein is a large superficial vein that ascends from the hand along the anterior-lateral border of the forearm and arm to join with the axillary artery in the axilla. It drains the hand, forearm, and arm.

Cephalic vein (right and left) [Veins of thorax, head, and upper extremity]

The right common carotid artery is a terminal branch of the brachiocephalic trunk and the left common carotid artery is the second branch of the aortic arch. The right and left common carotid arteries branch from different vessels, but both vessels are located in the anterior-lateral region of the neck on their respective sides of the body. They ultimately bifurcate into a (right and left) external and internal carotid artery at the superior border of the laryngeal thyroid cartilage. It supplies blood to the internal and external carotid arteries.

Common carotid artery (right and left) [Arteries of thorax, head, and upper extremity]

The deep brachial artery is a proximal branch of the brachial artery. It courses posterior (deep) to pass between the medial and lateral heads of the triceps brachii, spirals around the shaft of the humerus between the humerus and the triceps brachii muscle, and joins with other vessels at the lateral elbow. It supplies oxygenated blood to the posterior arm.

Deep brachial artery (right and left) (a.k.a. deep artery of the arm) [Arteries of thorax, head, and upper extremity]

the arteries closest to the heart (aorta, aortic branches, and pulmonary trunk). Because of their proximity to the heart, these vessels are exposed to blood that is flowing through the lumen under high pressure. It is for this reason that the tunica media consists of a larger proportion of elastic tissue relative to smooth muscle. The extensive elastic tissue allows the vessel to stretch during ventricular contraction and recoil during ventricular relaxation. The recoiling of elastic tissue propels blood through the circulation when the heart is not actively pumping blood. The extensive circularly oriented fenestrated elastic sheets are interspersed with circularly oriented smooth muscle cells.

Elastic arteries or conducting arteries [histological features of arterioles and types of arteries]

The external carotid artery is one of the terminal branches of the common carotid artery. It gives off several branches along its course and ends by branching into two vessels that supply the external head and face. It supplies blood to the neck (larynx, pharynx), face, tongue, and external head.

External carotid artery (right and left) [Arteries of thorax, head, and upper extremity]

The external jugular vein descends through the neck superficial to the sternocleidomastoid muscle and drains into the subclavian vein. It drains blood from the exterior of the skull, neck, and face.

External jugular (right and left) [Veins of thorax, head, and upper extremity]

The internal carotid artery is one of the terminal branches of the common carotid artery. It enters into the skull through the carotid canal in the temporal bone, joins with vessels that form the circle of Willis, and forms terminal branches that supply the brain with oxygenated blood. It is the primary blood supply to the brain. It branches into the anterior and middle cerebral arteries, which are joined to the circle of Willis by vessel connections called communicating arteries.

Internal carotid artery (right and left) [Arteries of thorax, head, and upper extremity]

The internal jugular vein exits the skull through the jugular foramen and descends the neck alongside the common carotid artery. It joins with the subclavian vein to form the brachiocephalic vein. It mainly drains blood from the cranial cavity.

Internal jugular vein (right and left) [Veins of thorax, head, and upper extremity]

The median cubital vein is a superficial vein that connects the basilica and cephalic veins in the region or the cubital fossa. This vessel is often used as a site from which to draw blood during venipuncture.

Median cubital vein (right and left) [Veins of thorax, head, and upper extremity]

most of the named arteries in the body excluding the immediate branches of the aorta. The tunica media of a muscular artery consists mostly of smooth muscle with some sheets of fenestrated elastic tissue between the muscular layers.

Muscular arteries or distributing arteries [histological features of arterioles and types of arteries]

The radial artery is a terminal branch of the brachial artery. It courses through the forearm on the lateral side (thumb side) to the wrist where it is palpable as the radial pulse medial. At the wrist, it divides into a superficial branch and deep branch that continue into the hand to connect with the superficial and deep palmar arches It supplies oxygenated blood to the elbow, forearm, hand, and digits.

Radial artery (right and left) [Arteries of thorax, head, and upper extremity]

The radial veins surround and parallel the radial artery and join the ulnar veins in the cubital fossa to drain blood into the brachial veins. It drains blood from the hand and lateral forearm.

Radial veins (right and left) [Veins of thorax, head, and upper extremity]

The subclavian vein is a continuation of the axillary vein. It changes name after the axillary vein crosses the first rib. It drains blood from the axillary vein.

Subclavian vein (right and left) [Veins of thorax, head, and upper extremity]

The right subclavian artery is a branch of the brachiocephalic artery, and the left subclavian is the third branch of the aortic arch. The right and left subclavian arteries branch from different vessels, but both vessels course in a superior and lateral direction from their origins to cross the first rib, and when they do; their name changes to the axillary arteries. They supply blood to the brain, neck, shoulder, chest, and upper limb.

Sublcavian artery (right and left) [Arteries of thorax, head, and upper extremity]

The lateral (thumb side) of the arches are supplied by the radial artery, and the medial side of the arches are supplied by the ulnar artery. Both arches course through the hand. Branches of the arches supply the hand and fingers.

Superficial and deep palmar arches [Arteries of thorax, head, and upper extremity]

The brachiocephalic veins join to form the superior vena cava. It drains blood from the upper extremity and the head.

Superior vena cava [Veins of thorax, head, and upper extremity]

The ulnar artery is a terminal branch of the brachial artery. It arises as a terminal branch of the brachial artery and courses through the anterior forearm on the medial side. At the wrist, the ulnar artery divides into a superficial and deep branch that continues into the hand to connect with the superficial and deep palmar arches. It supplies the forearm, hand, and digits.

Ulnar artery (right and left) [Arteries of thorax, head, and upper extremity]

The ulnar veins surround and parallel the ulnar artery and join the radial veins in the cubital fossa to drain blood into the brachial veins. It drains blood from the hand and medial forearm.

Unlar veins (right and left)

the large vessels o f the venous circulation. Veins drain blood away from venules toward the heart. Veins are categorized into medium and large veins depending upon their size. Most named veins are medium sized veins that consist of a tunica media that is thinner than the tunica media of a medium sized artery. The thickest tunic of a medium sized vein is usually the tunica adventitia.

Veins [histological features of venule and vein]

small vessels of the venous circulation that transport blood from capillaries to larger veins. Venules receive blood from capillary beds under low pressure, so their walls lack smooth muscle. This lack of smooth muscle in the tunica media causes the wall to be thin and resemble capillary walls in histological section. However, venules are much larger in size than capillaries with a lumenal diameter ranging from 15-20 microns, which is about 2-3 times the diameter of a RBC

Venules [histological features of venule and vein]

The vertebral artery is the first branch from the subclavian artery. It ascends in the neck through transverse foramina of the cervical vertebrae to enter the skull through the foramen magnum. When in the skull, the right and left vertebral arteries join anterior to the brainstem to form the basilar artery. Recall from A&P I (Brain Lab) that that the vertebral arteries supply blood to the basilar artery, which is the main blood supply to the brainstem and also supplies blood to the circle of Willis.

Vertebral artery (right and left) [Arteries of thorax, head, and upper extremity]

a 180 degree left bend of the aorta that arches over the left primary bronchus. Three blood vessels branch from the aortic arch.

arch of aorta [Arteries of thorax, head, and upper extremity]

a large vessel that receives blood from the left ventricle. The only two branches of the ascending aortal are the left and right coronary arteries, which were described in more detail in the heart lab.

ascending aorta [Arteries of thorax, head, and upper extremity]

The first branch of the arch of aorta. It travels a short distance and bifurcates into the right common carotid artery and the right subclavian artery.

brachiocephalic trunk (artery) [Arteries of thorax, head, and upper extremity]

a simple squamous epithelium that lines the lumen of the blood vessel.

endothelium [3 major tunics and components that comprise walls of arteries and veins]

the innermost layer of fenestrated elastic tissue. The IEL is prominent in muscular arteries and large arterioles, but absent in small arterioles. In veins the IEL is thin, and in venules it is usually absent.

internal elastic lamina (IEL) [3 major tunics and components that comprise walls of arteries and veins]

branches from the left side of the ascending aorta

left coronary artery [Arteries of thorax, head, and upper extremity]

branches from the right side of the ascending aorta

right coronary artery [Arteries of thorax, head, and upper extremity]

a layer of loose connective tissue that supports the endothelium and can contain a few scattered smooth muscle cells.

subendothelial layer [3 major tunics and components that comprise walls of arteries and veins]

The (descending) thoracic aorta is the continuation of the aortic arch and descends in the posterior mediastinum to the diaphragm.

thoracic aorta [Arteries of thorax, head, and upper extremity]

the outermost layer of the vessel wall. It consists of longitudinally arranged collagen and a few elastic fibers that gradually merge with loose connective tissue surrounding the vessel. The thickness of the adventitia ranges from a relatively thin layer in most arteries to a thick layer in venules and veins where it is the thickest of the three tunics.

tunica adventitia or tunica externa [3 major tunics and components that comprise walls of arteries and veins]

the innermost layer of the blood vessel

tunica intima [3 major tunics and components that comprise walls of arteries and veins]

the middle layer of the blood vessel wall and varies greatly in vessels of different size and type. It consists mostly of circularly arranged smooth muscle cells and fenestrated sheets of elastic tissue. The outermost layer of elastic tissue in the media is called the external elastic lamina. The relative proportion of elastic tissue and smooth muscle in arteries varies depending upon the type of artery (elastic or muscular). In a vein that is of comparable size to an artery, the vein has a considerably thinner tunica media.

tunica media [3 major tunics and components that comprise walls of arteries and veins]

Veins also contain valves that prevent the backflow of blood.

valves [histological features of venule and vein]